/*!
 * Copyright 2012, Chris Wanstrath
 * Released under the MIT License
 * https://github.com/defunkt/jquery-pjax
 */

(function ($) {

	// When called on a container with a selector, fetches the href with
	// ajax into the container or with the data-pjax attribute on the link
	// itself.
	//
	// Tries to make sure the back button and ctrl+click work the way
	// you'd expect.
	//
	// Exported as $.fn.pjax
	//
	// Accepts a jQuery ajax options object that may include these
	// pjax specific options:
	//
	//
	// container - Where to stick the response body. Usually a String selector.
	//             $(container).html(xhr.responseBody)
	//             (default: current jquery context)
	//      push - Whether to pushState the URL. Defaults to true (of course).
	//   replace - Want to use replaceState instead? That's cool.
	//
	// For convenience the second parameter can be either the container or
	// the options object.
	//
	// Returns the jQuery object
	var pjaxWaiting = {};

	function fnPjax(selector, container, options) {
		var context = this;
		return this.on('click.pjax', selector, function (event) {
			var opts = $.extend({}, optionsFor(container, options)),
				dataPjax = $(this).attr('data-pjax');
			if (!opts.container)
				if (dataPjax === '')
					opts.container = '#fc-pageContent';
				else
					opts.container = $(this).attr('data-pjax') || context;
			handleClick(event, opts)
		})
	}

	// Public: pjax on click handler
	//
	// Exported as $.pjax.click.
	//
	// event   - "click" jQuery.Event
	// options - pjax options
	//
	// Examples
	//
	//   $(document).on('click', 'a', $.pjax.click)
	//   // is the same as
	//   $(document).pjax('a')
	//
	//  $(document).on('click', 'a', function(event) {
	//    var container = $(this).closest('[data-pjax-container]')
	//    $.pjax.click(event, container)
	//  })
	//
	// Returns nothing.
	function handleClick(event, container, options) {
		options = optionsFor(container, options);
		// TODO: 取到了a标签
		var link = event.currentTarget;

		if (link.tagName.toUpperCase() !== 'A')
			throw "$.fn.pjax or $.pjax.click requires an anchor element";

		// Middle click, cmd click, and ctrl click should open
		// links in a new tab as normal.
		if (event.which > 1 || event.metaKey || event.ctrlKey || event.shiftKey || event.altKey)
			return;

		// Ignore cross origin links
		if (location.protocol !== link.protocol || location.hostname !== link.hostname)
			return;

		// Ignore case when a hash is being tacked on the current URL
		if (link.href.indexOf('#') > -1 && stripHash(link) == stripHash(location))
			return;

		// Ignore event with default prevented
		if (event.isDefaultPrevented())
			return;

		var defaults = {
			url: link.href,
			container: $(link).attr('data-pjax'),
			target: link
		};

		var opts = $.extend({}, defaults, options);
		var clickEvent = $.Event('pjax:click');
		$(link).trigger(clickEvent, [opts]);

		pjaxWaiting.link = opts;
		if (pjaxWaiting.script && pjaxWaiting.script.length !== 0) {
			event.preventDefault();
			return;
		}

		if (!clickEvent.isDefaultPrevented()) {
			pjax(opts);
			event.preventDefault();
			$(link).trigger('pjax:clicked', [opts])
		}
	}

	// Public: pjax on form submit handler
	//
	// Exported as $.pjax.submit
	//
	// event   - "click" jQuery.Event
	// options - pjax options
	//
	// Examples
	//
	//  $(document).on('submit', 'form', function(event) {
	//    var container = $(this).closest('[data-pjax-container]')
	//    $.pjax.submit(event, container)
	//  })
	//
	// Returns nothing.
	function handleSubmit(event, container, options) {
		options = optionsFor(container, options);

		var form = event.currentTarget;
		var $form = $(form);

		if (form.tagName.toUpperCase() !== 'FORM')
			throw "$.pjax.submit requires a form element";

		var defaults = {
			type: ($form.attr('method') || 'GET').toUpperCase(),
			url: $form.attr('action'),
			container: $form.attr('data-pjax'),
			target: form
		};

		if (defaults.type !== 'GET' && window.FormData !== undefined) {
			defaults.data = new FormData(form);
			defaults.processData = false;
			defaults.contentType = false;
		} else {
			// Can't handle file uploads, exit
			if ($(form).find(':file').length) {
				return;
			}

			// Fallback to manually serializing the fields
			defaults.data = $(form).serializeArray();
		}

		pjax($.extend({}, defaults, options));

		event.preventDefault()
	}

	// Loads a URL with ajax, puts the response body inside a container,
	// then pushState()'s the loaded URL.
	//
	// Works just like $.ajax in that it accepts a jQuery ajax
	// settings object (with keys like url, type, data, etc).
	//
	// Accepts these extra keys:
	//
	// container - Where to stick the response body.
	//             $(container).html(xhr.responseBody)
	//      push - Whether to pushState the URL. Defaults to true (of course).
	//   replace - Want to use replaceState instead? That's cool.
	//
	// Use it just like $.ajax:
	//
	//   var xhr = $.pjax({ url: this.href, container: '#main' })
	//   console.log( xhr.readyState )
	//
	// Returns whatever $.ajax returns.
	function pjax(options) {
		options = $.extend(true, {}, $.ajaxSettings, pjax.defaults, options);

		if ($.isFunction(options.url)) {
			options.url = options.url()
		}

		var target = options.target;

		var hash = parseURL(options.url).hash;

		var context = options.context = findContainerFor(options.container);

		// We want the browser to maintain two separate internal caches: one
		// for pjax'd partial page loads and one for normal page loads.
		// Without adding this secret parameter, some browsers will often
		// confuse the two.
		if (!options.data) options.data = {};
		if ($.isArray(options.data)) {
			options.data.push({
				name: '_pjax',
				value: context.selector
			})
		} else {
			options.data._pjax = context.selector
		}

		function fire(type, args, props) {
			if (!props) props = {};
			props.relatedTarget = target;
			var event = $.Event(type, props);
			context.trigger(event, args);
			return !event.isDefaultPrevented()
		}

		var timeoutTimer;

		options.beforeSend = function (xhr, settings) {
			// No timeout for non-GET requests
			// Its not safe to request the resource again with a fallback method.
			if (settings.type !== 'GET') {
				settings.timeout = 0
			}

			xhr.setRequestHeader('X-PJAX', 'true');
			xhr.setRequestHeader('X-PJAX-Container', context.selector);

			if (!fire('pjax:beforeSend', [xhr, settings]))
				return false;

			if (settings.timeout > 0) {
				timeoutTimer = setTimeout(function () {
					if (fire('pjax:timeout', [xhr, options]))
						xhr.abort('timeout')
				}, settings.timeout);

				// Clear timeout setting so jquerys internal timeout isn't invoked
				settings.timeout = 0
			}

			var url = parseURL(settings.url);
			if (hash) url.hash = hash;
			options.requestUrl = stripInternalParams(url)
		};

		options.complete = function (xhr, textStatus) {
			if (timeoutTimer)
				clearTimeout(timeoutTimer);

			fire('pjax:complete', [xhr, textStatus, options]);

			fire('pjax:end', [xhr, options])
		};

		options.error = function (xhr, textStatus, errorThrown) {
			var container = extractContainer("", xhr, options);

			var allowed = fire('pjax:error', [xhr, textStatus, errorThrown, options]);
			if (options.type == 'GET' && textStatus !== 'abort' && allowed) {
				locationReplace(container.url)
			}
		};

		options.success = function (data, status, xhr) {
			var previousState = pjax.state;

			// If $.pjax.defaults.version is a function, invoke it first.
			// Otherwise it can be a static string.
			var currentVersion = (typeof $.pjax.defaults.version === 'function') ?
				$.pjax.defaults.version() :
				$.pjax.defaults.version;

			var latestVersion = xhr.getResponseHeader('X-PJAX-Version');
			var container = extractContainer(data, xhr, options);

			var url = parseURL(container.url);
			if (hash) {
				url.hash = hash;
				container.url = url.href
			}

			// If there is a layout version mismatch, hard load the new url
			if (currentVersion && latestVersion && currentVersion !== latestVersion) {
				locationReplace(container.url);
				return
			}

			// If the new response is missing a body, hard load the page
			if (!container.contents) {
				locationReplace(container.url);
				return
			}

			pjax.state = {
				id: options.id || uniqueId(),
				url: container.url,
				title: container.title,
				container: context.selector,
				fragment: options.fragment,
				timeout: options.timeout
			};

			if (options.push || options.replace) {
				window.history.replaceState(pjax.state, container.title, options.href)
			}

			// Only blur the focus if the focused element is within the container.
			var blurFocus = $.contains(options.container, document.activeElement);

			// Clear out any focused controls before inserting new page contents.
			if (blurFocus) {
				try {
					document.activeElement.blur()
				} catch (e) { }
			}

			if (container.title) document.title = container.title;

			fire('pjax:beforeReplace', [container.contents, options], {
				state: pjax.state,
				previousState: previousState
			});

			context.html(container.contents);

			// FF bug: Won't autofocus fields that are inserted via JS.
			// This behavior is incorrect. So if theres no current focus, autofocus
			// the last field.
			//
			// http://www.w3.org/html/wg/drafts/html/master/forms.html
			var autofocusEl = context.find('input[autofocus], textarea[autofocus]').last()[0];
			if (autofocusEl && document.activeElement !== autofocusEl) {
				autofocusEl.focus();
			}

			executeScriptTags(context, container.scripts);

			var scrollTo = options.scrollTo;

			// Ensure browser scrolls to the element referenced by the URL anchor
			if (hash) {
				var name = decodeURIComponent(hash.slice(1));
				var target = document.getElementById(name) || document.getElementsByName(name)[0];
				if (target) scrollTo = $(target).offset().top
			}

			if (typeof scrollTo == 'number') $(window).scrollTop(scrollTo);

			fire('pjax:success', [data, status, xhr, options])
		};


		// Initialize pjax.state for the initial page load. Assume we're
		// using the container and options of the link we're loading for the
		// back button to the initial page. This ensures good back button
		// behavior.
		if (!pjax.state) {
			pjax.state = {
				id: uniqueId(),
				url: window.location.href,
				title: document.title,
				container: context.selector,
				fragment: options.fragment,
				timeout: options.timeout
			};
			window.history.replaceState(pjax.state, document.title)
		}

		// Cancel the current request if we're already pjaxing
		abortXHR(pjax.xhr);

		pjax.options = options;
		options.href = options.url;
		options.type = "GET";
		//============================================= 
		var params = u.parseQueryString(options.url);
		var key = params.key;
		if (!key) {
			console.warn('未检测到url包含关键字key')
		}

		options.url = router.get(key) + `?${u.toUrl(params)}`;

		//=============================================  
		var xhr = pjax.xhr = $.ajax(options);

		if (xhr.readyState > 0) {
			if (options.push && !options.replace) {
				if (location.href.match(/\/work.*/)[0] != options.href) {
					cachePush(pjax.state.id, cloneContents(context));
					window.history.pushState(null, "", options.href);
				}
			}

			fire('pjax:start', [xhr, options]);
			fire('pjax:send', [xhr, options])
		}

		return pjax.xhr
	}

	// Public: Reload current page with pjax.
	//
	// Returns whatever $.pjax returns.
	function pjaxReload(container, options) {
		var defaults = {
			url: window.location.href,
			push: false,
			replace: true,
			scrollTo: false
		};

		return pjax($.extend(defaults, optionsFor(container, options)))
	}

	// Internal: Hard replace current state with url.
	//
	// Work for around WebKit
	//   https://bugs.webkit.org/show_bug.cgi?id=93506
	//
	// Returns nothing.
	function locationReplace(url) {
		window.history.replaceState(null, "", pjax.state.url);
		window.location.replace(url)
	}


	var initialPop = true;
	var initialURL = window.location.href;
	var initialState = window.history.state;

	// Initialize $.pjax.state if possible
	// Happens when reloading a page and coming forward from a different
	// session history.
	if (initialState && initialState.container) {
		pjax.state = initialState
	}

	// Non-webkit browsers don't fire an initial popstate event
	if ('state' in window.history) {
		initialPop = false
	}

	// popstate handler takes care of the back and forward buttons
	//
	// You probably shouldn't use pjax on pages with other pushState
	// stuff yet.
	function onPjaxPopstate(event) {

		// Hitting back or forward should override any pending PJAX request.
		if (!initialPop) {
			abortXHR(pjax.xhr)
		}

		var previousState = pjax.state;
		var state = event.state;
		var direction;

		if (state && state.container) {
			// When coming forward from a separate history session, will get an
			// initial pop with a state we are already at. Skip reloading the current
			// page.
			if (initialPop && initialURL == state.url) return;

			if (previousState) {
				// If popping back to the same state, just skip.
				// Could be clicking back from hashchange rather than a pushState.
				if (previousState.id === state.id) return;

				// Since state IDs always increase, we can deduce the navigation direction
				direction = previousState.id < state.id ? 'forward' : 'back'
			}

			var cache = cacheMapping[state.id] || [];
			cache = [];
			var container = $(cache[0] || state.container),
				contents = cache[1];

			if (container.length) {
				if (previousState) {
					// Cache current container before replacement and inform the
					// cache which direction the history shifted.
					cachePop(direction, previousState.id, cloneContents(container))
				}

				var popstateEvent = $.Event('pjax:popstate', {
					state: state,
					direction: direction
				});
				container.trigger(popstateEvent);

				var options = {
					id: state.id,
					url: state.url,
					container: container,
					push: false,
					fragment: state.fragment,
					timeout: state.timeout,
					scrollTo: false
				};

				if (contents) {
					container.trigger('pjax:start', [null, options]);

					pjax.state = state;
					if (state.title) document.title = state.title;
					var beforeReplaceEvent = $.Event('pjax:beforeReplace', {
						state: state,
						previousState: previousState
					});
					container.trigger(beforeReplaceEvent, [contents, options]);
					container.html(contents);

					container.trigger('pjax:end', [null, options])
				} else {
					pjax(options)
				}

				// Force reflow/relayout before the browser tries to restore the
				// scroll position.
				container[0].offsetHeight
			} else {
				locationReplace(location.href)
			}
		}
		initialPop = false
	}

	// Fallback version of main pjax function for browsers that don't
	// support pushState.
	//
	// Returns nothing since it retriggers a hard form submission.
	function fallbackPjax(options) {
		var url = $.isFunction(options.url) ? options.url() : options.url,
			method = options.type ? options.type.toUpperCase() : 'GET';

		var form = $('<form>', {
			method: method === 'GET' ? 'GET' : 'POST',
			action: url,
			style: 'display:none'
		});

		if (method !== 'GET' && method !== 'POST') {
			form.append($('<input>', {
				type: 'hidden',
				name: '_method',
				value: method.toLowerCase()
			}))
		}

		var data = options.data;
		if (typeof data === 'string') {
			$.each(data.split('&'), function (index, value) {
				var pair = value.split('=');
				form.append($('<input>', {
					type: 'hidden',
					name: pair[0],
					value: pair[1]
				}))
			})
		} else if ($.isArray(data)) {
			$.each(data, function (index, value) {
				form.append($('<input>', {
					type: 'hidden',
					name: value.name,
					value: value.value
				}))
			})
		} else if (typeof data === 'object') {
			var key;
			for (key in data)
				form.append($('<input>', {
					type: 'hidden',
					name: key,
					value: data[key]
				}))
		}

		$(document.body).append(form);
		form.submit()
	}

	// Internal: Abort an XmlHttpRequest if it hasn't been completed,
	// also removing its event handlers.
	function abortXHR(xhr) {
		if (xhr && xhr.readyState < 4) {
			xhr.onreadystatechange = $.noop;
			xhr.abort()
		}
	}

	// Internal: Generate unique id for state object.
	//
	// Use a timestamp instead of a counter since ids should still be
	// unique across page loads.
	//
	// Returns Number.
	function uniqueId() {
		return (new Date).getTime()
	}

	function cloneContents(container) {
		var cloned = container.clone();
		// Unmark script tags as already being eval'd so they can get executed again
		// when restored from cache. HAXX: Uses jQuery internal method.
		cloned.find('script').each(function () {
			if (!this.src) jQuery._data(this, 'globalEval', false)
		});
		return [container.selector, cloned.contents()]
	}

	// Internal: Strip internal query params from parsed URL.
	//
	// Returns sanitized url.href String.
	function stripInternalParams(url) {
		url.search = url.search.replace(/([?&])(_pjax|_)=[^&]*/g, '');
		return url.href.replace(/\?($|#)/, '$1')
	}

	// Internal: Parse URL components and returns a Locationish object.
	//
	// url - String URL
	//
	// Returns HTMLAnchorElement that acts like Location.
	function parseURL(url) {
		var a = document.createElement('a');
		a.href = url;
		return a
	}

	// Internal: Return the `href` component of given URL object with the hash
	// portion removed.
	//
	// location - Location or HTMLAnchorElement
	//
	// Returns String
	function stripHash(location) {
		return location.href.replace(/#.*/, '')
	}

	// Internal: Build options Object for arguments.
	//
	// For convenience the first parameter can be either the container or
	// the options object.
	//
	// Examples
	//
	//   optionsFor('#container')
	//   // => {container: '#container'}
	//
	//   optionsFor('#container', {push: true})
	//   // => {container: '#container', push: true}
	//
	//   optionsFor({container: '#container', push: true})
	//   // => {container: '#container', push: true}
	//
	// Returns options Object.
	function optionsFor(container, options) {
		// Both container and options
		if (container && options)
			options.container = container;

		// First argument is options Object
		else if ($.isPlainObject(container))
			options = container;

		// Only container
		else
			options = {
				container: container
			};

		// Find and validate container
		if (options.container)
			options.container = findContainerFor(options.container);

		return options
	}

	// Internal: Find container element for a variety of inputs.
	//
	// Because we can't persist elements using the history API, we must be
	// able to find a String selector that will consistently find the Element.
	//
	// container - A selector String, jQuery object, or DOM Element.
	//
	// Returns a jQuery object whose context is `document` and has a selector.
	function findContainerFor(container) {
		container = $(container);

		if (!container.length) {
			throw "no pjax container for " + container.selector
		} else if (container.selector !== '' && container.context === document) {
			return container
		} else if (container.attr('id')) {
			return $('#' + container.attr('id'))
		} else {
			throw "cant get selector for pjax container!"
		}
	}

	// Internal: Filter and find all elements matching the selector.
	//
	// Where $.fn.find only matches descendants, findAll will test all the
	// top level elements in the jQuery object as well.
	//
	// elems    - jQuery object of Elements
	// selector - String selector to match
	//
	// Returns a jQuery object.
	function findAll(elems, selector) {
		return elems.filter(selector).add(elems.find(selector));
	}

	function parseHTML(html) {
		return $.parseHTML(html, document, true)
	}

	// Internal: Extracts container and metadata from response.
	//
	// 1. Extracts X-PJAX-URL header if set
	// 2. Extracts inline <title> tags
	// 3. Builds response Element and extracts fragment if set
	//
	// data    - String response data
	// xhr     - XHR response
	// options - pjax options Object
	//
	// Returns an Object with url, title, and contents keys.
	function extractContainer(data, xhr, options) {
		//----------------------------
		//添加随机数
		if (isDebug && isDebug === true) {
			data = data.replace(/\.js\"\>/g, '.js?v=' + parseInt(Math.random() * 1000000000) + '">');
		}
		//----------------------------

		var obj = {},
			fullDocument = /<html/i.test(data);

		// Prefer X-PJAX-URL header if it was set, otherwise fallback to
		// using the original requested url.
		var serverUrl = xhr.getResponseHeader('X-PJAX-URL');
		obj.url = serverUrl ? stripInternalParams(parseURL(serverUrl)) : options.requestUrl;

		// Attempt to parse response html into elements
		if (fullDocument) {
			var $head = $(parseHTML(data.match(/<head[^>]*>([\s\S.]*)<\/head>/i)[0]));
			var $body = $(parseHTML(data.match(/<body[^>]*>([\s\S.]*)<\/body>/i)[0]))
		} else {
			var $head = $body = $(parseHTML(data))
		}

		// If response data is empty, return fast
		if ($body.length === 0)
			return obj;

		// If there's a <title> tag in the header, use it as
		// the page's title.
		obj.title = findAll($head, 'title').first().text();

		if (options.fragment) {
			// If they specified a fragment, look for it in the response
			// and pull it out.
			if (options.fragment === 'body') {
				var $fragment = $body
			} else {
				var $fragment = findAll($body, options.fragment).first()
			}

			if ($fragment.length) {
				obj.contents = options.fragment === 'body' ? $fragment : $fragment.contents();

				// If there's no title, look for data-title and title attributes
				// on the fragment
				if (!obj.title)
					obj.title = $fragment.attr('title') || $fragment.data('title')
			}

		} else if (!fullDocument) {
			obj.contents = $body
		}

		// Clean up any <title> tags
		if (obj.contents) {
			// Remove any parent title elements
			obj.contents = obj.contents.not(function () {
				return $(this).is('title')
			});

			obj.contents = obj.contents.not(function () {
				return $(this).is('meta')
			});

			// Then scrub any titles from their descendants
			obj.contents.find('title').remove();
			obj.contents.find('meta').remove();

			// Gather all script[src] elements
			//obj.scripts = findAll(obj.contents, 'script[src]').remove();
			//obj.contents = obj.contents.not(obj.scripts)
		}

		// Trim any whitespace off the title
		if (obj.title) obj.title = $.trim(obj.title);

		return obj
	}

	// Load an execute scripts using standard script request.
	//
	// Avoids jQuery's traditional $.getScript which does a XHR request and
	// globalEval.
	//
	// scripts - jQuery object of script Elements
	//
	// Returns nothing.
	function executeScriptTags(e, scripts) {
		pjaxWaiting.link = '';
		if (!scripts) return;

		var existingScripts = $('script[src]');

		pjaxWaiting.script = Array.isArray(scripts) ? scripts : scripts.toArray();
		scriptLoad(existingScripts, scripts);

		var timer = setInterval(function () {
			if (pjaxWaiting.script.length === 0) {
				clearInterval(timer);
				$.Event('pjax:callback');
				$(e).trigger('pjax:callback');
				if (pjaxWaiting.link !== '') {
					pjax(pjaxWaiting.link);
				}
			}
		}, 5);

		/*setTimeout(function(){
		 if(pjaxWaiting.link !== ''){
		 console.log(1)
		 //pjax(pjaxWaiting.link);
		 }
		 },500);*/
		/*if(pjaxWaiting.link !== ''){
		 pjaxWaiting.link = '';
		 pjax(opts);
		 }*/
	}

	function scriptLoad(e, scripts) {
		var fn = arguments.callee;
		if (scripts.length === 0) return;

		$.each(scripts, function (i, n) {
			var $item = $(n),
				src = $item.prop('src'),
				deps = $item.data('deps');

			/*var matchedScripts = e.filter(function () {
			 return this.src === src
			 });
			 if (matchedScripts.length) return;*/

			if (deps) {
				var waitLo = waitLoad(deps, pjaxWaiting.script);
				var len = scripts.length;
				if (waitLo !== 0) {
					setTimeout(function () {
						for (var v = 0; v < len; v++) {
							if (scripts[0] === '') scripts.splice(0, 1);
						}
						fn(e, scripts);
					}, 5);
					return false;
				} else {
					scripts.splice(i, 1, '');
				}
			} else {
				scripts.splice(i, 1, '');
			}

			var script = document.createElement('script');
			script.src = src;

			if (script.readyState) { //IE
				script.onreadystatechange = function () {
					if (script.readyState == "loaded" || script.readyState == "complete") {
						script.onreadystatechange = null;
						for (var f = 0; f < pjaxWaiting.script.length; f++) {
							if (pjaxWaiting.script[f].src === this.src) pjaxWaiting.script.splice(f, 1);
						}
					}
				};
			} else { //Others
				script.onload = function () {
					for (var f = 0; f < pjaxWaiting.script.length; f++) {
						if (pjaxWaiting.script[f].src === this.src) pjaxWaiting.script.splice(f, 1);
					}
				};
			}

			document.head.appendChild(script);
		});
	}

	function waitLoad(deps, wait) {
		deps = deps.split(',');

		var unload = [];

		for (var i = 0; i < deps.length; i++) {
			for (var n = 0; n < wait.length; n++) {
				if (deps[i] === $(wait[n]).data('name')) unload.push('wait');
			}
		}
		return unload.length;
	}

	// Internal: History DOM caching class.
	var cacheMapping = {};
	var cacheForwardStack = [];
	var cacheBackStack = [];

	// Push previous state id and container contents into the history
	// cache. Should be called in conjunction with `pushState` to save the
	// previous container contents.
	//
	// id    - State ID Number
	// value - DOM Element to cache
	//
	// Returns nothing.
	function cachePush(id, value) {
		cacheMapping[id] = value;
		cacheBackStack.push(id);

		// Remove all entries in forward history stack after pushing a new page.
		trimCacheStack(cacheForwardStack, 0);

		// Trim back history stack to max cache length.
		trimCacheStack(cacheBackStack, pjax.defaults.maxCacheLength)
	}

	// Shifts cache from directional history cache. Should be
	// called on `popstate` with the previous state id and container
	// contents.
	//
	// direction - "forward" or "back" String
	// id        - State ID Number
	// value     - DOM Element to cache
	//
	// Returns nothing.
	function cachePop(direction, id, value) {
		var pushStack, popStack;
		cacheMapping[id] = value;

		if (direction === 'forward') {
			pushStack = cacheBackStack;
			popStack = cacheForwardStack
		} else {
			pushStack = cacheForwardStack;
			popStack = cacheBackStack
		}

		pushStack.push(id);
		if (id = popStack.pop())
			delete cacheMapping[id];

		// Trim whichever stack we just pushed to to max cache length.
		trimCacheStack(pushStack, pjax.defaults.maxCacheLength)
	}

	// Trim a cache stack (either cacheBackStack or cacheForwardStack) to be no
	// longer than the specified length, deleting cached DOM elements as necessary.
	//
	// stack  - Array of state IDs
	// length - Maximum length to trim to
	//
	// Returns nothing.
	function trimCacheStack(stack, length) {
		while (stack.length > length)
			delete cacheMapping[stack.shift()]
	}

	// Public: Find version identifier for the initial page load.
	//
	// Returns String version or undefined.
	function findVersion() {
		return $('meta').filter(function () {
			var name = $(this).attr('http-equiv');
			return name && name.toUpperCase() === 'X-PJAX-VERSION'
		}).attr('content')
	}

	// Install pjax functions on $.pjax to enable pushState behavior.
	//
	// Does nothing if already enabled.
	//
	// Examples
	//
	//     $.pjax.enable()
	//
	// Returns nothing.
	function enable() {
		$.fn.pjax = fnPjax;
		$.pjax = pjax;
		$.pjax.enable = $.noop;
		$.pjax.disable = disable;
		$.pjax.click = handleClick;
		$.pjax.submit = handleSubmit;
		$.pjax.reload = pjaxReload;
		$.pjax.defaults = {
			timeout: 30000,
			push: true,
			replace: false,
			type: 'GET',
			dataType: 'html',
			scrollTo: 0,
			maxCacheLength: 20,
			version: findVersion
		};
		$(window).on('popstate.pjax', onPjaxPopstate)
	}

	// Disable pushState behavior.
	//
	// This is the case when a browser doesn't support pushState. It is
	// sometimes useful to disable pushState for debugging on a modern
	// browser.
	//
	// Examples
	//
	//     $.pjax.disable()
	//
	// Returns nothing.
	function disable() {
		$.fn.pjax = function () {
			return this
		};
		$.pjax = fallbackPjax;
		$.pjax.enable = enable;
		$.pjax.disable = $.noop;
		$.pjax.click = $.noop;
		$.pjax.submit = $.noop;
		$.pjax.reload = function () {
			window.location.reload()
		};

		$(window).off('popstate.pjax', onPjaxPopstate)
	}


	// Add the state property to jQuery's event object so we can use it in
	// $(window).bind('popstate')
	if ($.inArray('state', $.event.props) < 0)
		$.event.props.push('state');

	// Is pjax supported by this browser?
	$.support.pjax =
		window.history && window.history.pushState && window.history.replaceState &&
		// pushState isn't reliable on iOS until 5.
		!navigator.userAgent.match(/((iPod|iPhone|iPad).+\bOS\s+[1-4]\D|WebApps\/.+CFNetwork)/);

	$.support.pjax ? enable() : disable()

})(jQuery);